h1{
    width: 400px;
    height: 100px;
    padding: 50px;
    margin: 1px;
    border: 1px solid #ffccdd;
}

span{
    width: 400px;
    height: 100px;
    padding: 10px;
    margin: 10px;
    border: 1px solid #0dd;
}
/*换为内联盒子
div{
    display: inline; 
}
*/

a{
    display: inline-block;
    width: 200px;
    height: 100px;
    border: 1px solid #cfcfcf;
}

a:hover{
    background-color: #000;
}

div.box_before{
    width: 350px;
    height: 30px;
    background-color: chartreuse;
}

div.box{
    width: 350px;
    height: 150px;
    margin: 25px;
    padding: 25px;
    border: 5px solid black;
}

div.box_after{
    width: 350px;
    height: 30px;
    background-color: chartreuse;
}